The other day in the clinic, I encountered a patient who often had fresh blood in his stool, and I always thought it was hemorrhoids, so I did not pay attention to it. Recently, the stool was not very regular, either not relieving the stool for several days, or diarrhea several times a day. After listening to the medical history, I put on a latex finger sleeve and did an anal finger examination, and found that the patient’s blood in the stool and change in stool habits were not due to hemorrhoids, but to rectal cancer. The large intestine is the “terminal point” of the digestive tract. After food is digested and absorbed by the oral cavity through the digestive organs such as the esophagus and stomach, it is formed into stool in the large intestine and excreted regularly. Therefore, the early symptom of colorectal cancer is the change in the regularity and nature of bowel movement. Under normal circumstances, everyone’s bowel movement has a certain regularity, either once a day or once every other day. After rectal cancer, the regular bowel habits change: constipation, once every three or four days; diarrhea, four to five times a day or even more; or alternating constipation and diarrhea; or the feeling of incomplete bowel movement and poor defecation after defecation. This alternation of constipation and diarrhea is a very important alarm signal from rectal cancer. Although the change in the regularity of bowel movement and stool characteristics is an alarm signal of colorectal cancer, but because hemorrhoids, anal fistula and other anorectal diseases also have the symptoms of blood in stool and change in the regularity of bowel movement, and people often do not want to think about the bad things such as cancer, they always think it is bleeding hemorrhoids, thus missing the good opportunity of early diagnosis and treatment. According to clinical data, the incidence of rectal cancer is increasing, the age of onset is advancing, and early cancer is easy to be misdiagnosed. Therefore, adults over 40 years old should go to hospital for examination if one of the following conditions occurs, so that early detection, early diagnosis and early treatment can be made to improve the survival rate after surgery. 1, people who have always had regular bowel movements have recently experienced a change in bowel habits, such as diarrhea, constipation, or alternating diarrhea and constipation, with a sense of bowel irregularity. 2.Changes in the nature of stool, such as loose stool, mucus stool, pus and blood stool or blood in the stool in bright red or jam color. 3.Abdominal distension, abdominal pain or other abdominal discomfort. 4.Anaemia, emaciation and weakness of “unknown cause”.